OFFSET
1,2
COMMENTS
Value of sum for m = 126 has been checked to be probably prime with the isprime functions of PARI and Maple V. Also checked with ECM - see link.
Note that m+1 must be prime and hence a(n) = A088856(n) - 1. Another way to compute the number is (m^(m + 1) - 1)/(m - 1). - T. D. Noe, Dec 15 2004
Value of sum for m = 126 has been certified prime with Primo. - Ryan Propper, Jul 11 2005
LINKS
Dario Alpern, Integer factorization calculator.
FORMULA
a(n) = A088856(n) - 1.
EXAMPLE
The number 6 is in this sequence because 6^0 + 6^1 + 6^2 + 6^3 + 6^4 + 6^5 + 6^6 = (6^7 - 1)/5 = 55987 is prime.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Dec 15 2004
EXTENSIONS
One more term from T. D. Noe, Dec 15 2004
Edited by Thomas Ordowski, Sep 02 2021
STATUS
approved